Extracellular antigens have been isolated from Streptococcus mitis, Streptococcus salivarius and group A streptococcal cultures grown in a synthetic medium. Analysis of the antigens was performed by immunoelectrophoretic and double diffusion techniques using rabbit immune sera. S. mitis cultures produced 10 antigens, S. salivarius six antigens and group A streptococcus 12 antigens, when tested with their corresponding antisera. S. mitis and S. salivarius antigens had only one common antigen when tested with antisera to both antigen pools. No cross reaction was found between the exo-antigens of group A and viridans streptococci. While the extracellular antigen pool of group A streptococci contained ribonuclease, deoxyribonuclease, hyaluronidase, diphosphopyridine-nucleotidase, streptokinase and streptolysin 0, that of S. mitis contained only ribonuclease and that of S. salivarius contained hyaluronidase and collagenase. Each of the three streptococcal antigen pools contained a hemosensitizing factor which sensitized mammalian cells to passive immune kill. Sonicates produced from the mitis, salivarius and group A streptococcus contained six antigens, most of which cross reacted with each other. S. mitis sonicates were separated into six fractions by ion exchange chromatography on ECTEOLA cellulose, and into three major fractions following gel-filtration on Sephadex 0-200 columns. Rabbits injected i.v. with sonicates derived from S. mitis developed cardiac and hepatic lesions which, in some cases, were accompanied by a steep rise in serum glutamic oxalacetic transaminase, sorbitol dehydrogenase and total lipids. The relationship of tissue damage to enzyme rise is discussed in relation to the possible early diagnosis of tissue damage following streptococcal infection.

Rabbits injected with streptococcal extracellular protein (SEP) developed degenerative and infiltrative lesions in the heart and liver, with coagulation necrosis and multinucleated giant cells in the latter organ. The majority of these rabbits also showed elevated levels of glutamic-oxalacetic transaminase, or of sorbitol dehydrogenase, and all showed elevated serum lipids. These biochemical indications of cell injury could be found within 2 to 4 hours after a first injection of SEP. No such biochemical or pathologic effects were found following an injection of heated SEP or a commercially available streptokinase-streptodornase preparation from group C streptococcal culture. In a preliminary fractionation of SEP all the activity was found in a fraction not adsorbed to DEAE cellulose at pH 7.4 (0.05 M P04). The active fraction contained at least five antigens and four of the known streptococcal enzymes. Injection of extracts of sonically disrupted streptococci produced similar biochemical and pathologic changes. There was some cross-reacting material between the sonicates and anti-SEP serum.

Intraartikuläre Injektion von Streptolysin-S-freien extrazellulären Produkten der Streptokokken Gruppe A verursacht eine zunächst akute, in der Folge aber subkutane Synovitis. Die Veränderungen gleichen denjenigen nach Injektion von Streptolollensonikaten, so dass angenommen wird, ausser Streptolysin S bedingen auch andere streptokokkale Faktoren eine Arthritis.